Detectives have launched a preliminary investigation into Saltire after concerns were flagged up in an anonymous letter to council leader Jim Logue.

Police Scotland said it is reviewing the claims which centre around contracts and the council’s procurement process, after the council contacted police about the firm.

A Police Scotland spokeswoman said: “North Lanarkshire Council has made Police Scotland aware of the allegations and the matter will be reviewed.”

A spokesman for North Lanarkshire Council added: “The council made Police Scotland aware of an historical piece of correspondence in relation to Saltire which we felt should be examined.

“As this is now a police matter it would be inappropriate to comment further.”

STV News said it understands the allegations are “wide ranging” and relate the council’s contract tender process. Councillors as well as council officials are understood to be implicated in the claims.

On receiving the anonymous letter last week, council leader Jim Logue said: “These allegations, which are detailed, concern some of the council’s procurement processes. If true, they are extremely serious.

“I immediately instructed Paul Jukes, the chief executive, to launch an investigation. That investigation, led by the council’s internal audit team, is already underway. Should the auditors find anything which substantiates these allegations that evidence will immediately be handed over to Police Scotland.

“The internal audit team are able to access all files held by any part of the council and all IT systems. The chief executive has also made Police Scotland aware of the allegations and investigation.

“It is essential that the people of North Lanarkshire are able to have full confidence in the way the council conducts its business and I am determined that we are transparent at all times. Although these are currently unsubstantiated, anonymous allegations I believe that it is right to carry out a full investigation and share any evidence which comes to light with the police.

“As that investigation is now under way, it would be inappropriate for the council to comment further‎.”

Saltire - its full name is Saltire Facilities Management Ltd - is one-third owned by North Lanarkshire Council, which has one member on its board. That member, until his resignation on March 31, was Labour veteran Jim Brooks. Saltire’s majority shareholder is a firm called ALH 86 Ltd registered in London and ultimately owned by a holding firm called ALHCO Group Ltd, whose sole shareholder is businessman called John Clarke.

The business supplies and fits central heating systems and related equipment, including to North Lanarkshire Council tenants. Its most recent annual accounts showed a turnover of just under £18m, just over half of which, some £9.5m, was goods and services provided to North Lanarkshire Council.